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M11.L01 — Rivalry and Excludability: The Four Types of Goods

Module: Module 11 — Public Goods and Common Resources Lesson: L01 of 05 Duration: ~30 minutes Level: Introductory Provenance: OpenStax Principles of Microeconomics 3e | Principles of Microeconomics (Curtis and Irvine)

Learning Objective

Distinguish between goods based on rivalry and excludability characteristics.

Understanding Rivalry and Excludability

Goods can be classified based on two key characteristics: rivalry and excludability. Rivalry means consumption by one person reduces availability for others (e.g., eating a sandwich). Excludability means it's possible to prevent non-payers from consuming the good (e.g., movie tickets).

In Australia, we encounter all four types: 1. Private goods: Rival and excludable (e.g., groceries from Woolworths) 2. Public goods: Non-rival and non-excludable (e.g., national defense) 3. Club goods: Non-rival but excludable (e.g., Foxtel pay TV) 4. Common resources: Rival but non-excludable (e.g., public fishing grounds)

Worked Example

Classifying Sydney's Transport Options 1. Private car: Private good (rival - only one driver; excludable - need to own/rent) 2. Public bus: Common resource during peak (rival - crowded; non-excludable - can't easily refuse riders) 3. Toll roads: Club good (non-rival - space for more cars; excludable - e-Tag required) 4. Harbor views: Public good (non-rival - many can enjoy; non-excludable - can't prevent viewing)

Common Misconception

"Public goods are just things the government provides"

Public goods are defined by their economic characteristics, not who provides them. While governments often provide public goods (like lighthouses), they also provide private goods (like Australia Post services).

Key Takeaways

  • Rivalry means one person's use reduces others' availability
  • Excludability means non-payers can be prevented from using
  • Four categories exist based on these traits
  • Australian examples demonstrate all types in daily life

Practice

  1. Is a Netflix subscription rival or non-rival? Excludable or non-excludable?
  2. Why are public parks often considered common resources rather than public goods?
  3. Give an Australian example of a good that changed categories (e.g., from common resource to club good)

Further Resources

Provenance: OpenStax Principles of Microeconomics 3e | Principles of Microeconomics (Curtis and Irvine)